By default Sencha Touch is not compatible with Ext JS definitions. This article shows how you can trick Ext JS to reuse your Ext JS models and stores in Touch.
After another day of Sencha Touch 2, I discovered that it is a little less compatible with Ext JS then hoped for. Quite annoying is that Ext JS models and stores are not compatible with Sencha Touch 2. And as I don't want to code them twice when building an Ext JS and Touch application, I looked for a solution and found it.